1. Field of the Invention
The present invention relates to a method of manufacturing an electronic device that includes the step of melting a bonding material with light.
2. Description of the Related Art
An electronic component such as a semiconductor element may be bonded to a first member, such as a substrate for supporting the electronic component, and thus unitized therewith for use. In this case, solder, for example, is used to bond the electronic component and the first member together. On the other hand, for an electronic device including an electronic component, a first member with the electronic component bonded thereto may be bonded to a second member. In this case also, solder, for example, is used to bond the first member and the second member together.
An example of electronic devices including the electronic component and the first and second members as mentioned above is a thermally-assisted magnetic recording head such as one disclosed in each of U.S. Patent Application Publication Nos. 2011/0228650 A1, 2012/0073120 A1, and 2012/0090162 A1.
The thermally-assisted magnetic recording heads disclosed in the above-listed three references each include a slider which slightly flies over the surface of a magnetic recording medium, and a light source unit. The slider has a waveguide through which light propagates. The light source unit includes a laser diode and a unit substrate for supporting the laser diode. The laser diode is bonded to the unit substrate via a first solder layer. The unit substrate is positioned so that emitted light from the laser diode will be incident on the incidence end face of the wave guide, and is bonded to the slider via a second solder layer. The laser diode, the unit substrate, and the slider of the thermally-assisted magnetic recording head correspond to the electronic component, the first member, and the second member mentioned above, respectively.
Each of the aforementioned three references discloses a method of manufacturing the thermally-assisted magnetic recording head in which the unit substrate with the laser diode already bonded thereto is positioned with respect to the slider and then bonded thereto. The references each further disclose a technology to heat and melt the second solder layer by applying laser light when bonding the unit substrate to the slider, such that the laser light passes through the unit substrate. The references list Si, GaAs, SiC, Al2O3—TiC, and SiO2 as examples of the material of the unit substrate. The references further teach the use of Nd-YAG laser light having a wavelength of 1064 nm as the laser light for heating the second solder layer.
A problem with the above-described technology will now be discussed. According to the above-described technology, part of the laser light passing through the unit substrate is absorbed by the unit substrate and transformed into heat. The heat is conducted not only to the second solder layer which is intended to be melted but also to the first solder layer which is not intended to be melted. If the heat is conducted to the first solder layer in a large quantity, the first solder layer may be melted to cause a change in the position of the laser diode relative to the unit substrate.
This problem applies not only to the manufacture of a thermally-assisted magnetic recording head including a laser diode, a unit substrate and a slider but also generally to the manufacture of an electronic device including an electronic component, a first member and a second member.